Pure water is an essential ingredient for the production of laundry, detergent and cleaning products. Yet water is a precious commodity. That is why the water centre at Werner & Mertz draws its water from its own 70-metre-deep well and treats it in a multi-stage process to permit its use in production as desalinated water. This is made possible by means of a so-called ‘RO system’ (‘RO’ = ‘reverse osmosis’). In reverse osmosis, a physical-technical process, water along with any salts it contains in solution is pressed through a semi-permeable membrane. This results in pure water, with the salts collecting in front of the membrane in a liquid concentrate. Compared to traditional techniques using hydrochloric acid and sodium hydroxide for desalination, our reverse osmosis system brings considerable relief to the environment: we can then eliminate the use of hazardous substances.
Effective use, high-quality recycling
Even our head office is supplied with its own well water. Heat exchangers provide air conditioning by drawing heat or cooling from ground water. As a portion of this water is then used in production, it is used twice. Water pumping is also coupled with the actual heat or cooling requirements in the building. This reduces the water consumption and hence the energy consumption devoted to pumping water.
The production waste water is mixed with lime and iron minerals and pressed through large filters. What remains is lime and ferrous filter sludge, but this does not end up in a landfill and is instead forwarded to the brick industry. There it is used as an aggregate in brick production and thus subject to high-quality recycling – entirely in keeping with our philosophy of sustainable recycling
Sustainable further development
To ensure that the production operation is supplied with demineralised water even under very heavy loads while minimising pressure fluctuations in the system, a second storage tank with a volume of 200 m³ was commissioned in early October 2015.
The installation of a fourth reverse osmosis (RO) system in early 2016 ensures the production of demineralised water even if more is needed in the production operation. Moreover, in May 2015 an online measurement instrument was installed in the waste water pre-treatment plant to record COD and TOC values in the inflow of waste water from the production areas. This enables immediate response to high loads, followed by separate waste water collection. The new procedure also eliminates the photometric measurement of COD concentrations in the inflow. The method previously used consumed approx. 100 mercury- and dichromate-containing test cuvettes each month, which we can now save.